A previously unknown underwater volcano has been discovered off the coast of Antarctica, the National Science Foundation said Thursday.

The finding helps explain mariners’ historical reports of discolored water in the area, the agency said. Material from underwater volcanoes is known to cause discoloration in water over them.

The presence of a volcano was first suggested in sonar studies during a research cruise in January, but scientists were unable to return to the stormy waters of the region until April.

The foundation said the research vessel Lawrence M. Gould was returning from a study of a collapsed ice shelf when it passed over the volcano.

The research team, led by Eugene Domack of Hamilton College in Clinton, N.Y., used a bottom-scanning video recorder, rock dredges and temperature probes to survey the sides and crest of the submarine peak.

Signs of fresh flows
While large areas were colonized by submarine life, none was found on dark rock around the volcano itself, indicating that lava had flowed fairly recently.

In addition, dredges recovered abundant fresh basalt, a volcanic rock. It normally would be rapidly acted upon and transformed by seawater.

Highly sensitive temperature probes moving continuously across the bottom of the volcano showed signs of geothermal heating of seawater, according to the agency.

Domack said the volcano stands 2,300 feet (700 meters) above the seafloor and extends to within roughly 900 feet (275 meters) of the ocean surface.

No previous activity notedThe volcano is in an area known as Antarctic Sound, at the northernmost tip of Antarctica. There is no previous scientific record of active volcanoes in the region where the new peak was discovered. The volcano is located on the continental shelf, in the vicinity of a deep trough carved out by glaciers passing across the seafloor.

In addition to Hamilton College, the team included researchers from Colgate University, the Lamont-Doherty Earth Observatory at Columbia University, Montclair State University in New Jersey, Southern Illinois University in Carbondale and Queens University in Canada.

The foundation is an independent federal agency that supports fundamental research in science and engineering. It manages the United States’ Antarctic research program.